(1)\Efforts will be made to find monoclonal antibodies that are directed against nuclear antigens whose levels change significantly during the G1 period of primary cultures of chick embryo fibroblasts (CEF). (2)\The study of the nonbasic polypeptides whose rates of synthesis in CEF are preferentially enhanced by insulin will be completed. (3)\The mRNAs that code for ribosomal proteins have been shown to be poorly initiated in insulin-deprived but not in insulin-treated CEF. Whether or not a similar control mechanism operates in mammalian cells in culture and in vivo will be explored. (4)\An attempt will be made to purify and identify a novel nucleotide whose rate of labeling is increased in resting CEF treated with insulin or serum.